<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>浮动布局</title>
    <style>
      .main::after{
          display: block;
          content: "";
          clear: both;
      }

        body{margin: 0;}
        .one,.two,.three{
            width: 300px;
            height: 100px;
            float:left;
        }
        .one{background-color: aqua;}
        .two{background-color: blue;}
        .three{background-color: blueviolet;}
    </style>
</head>
<body>
    <div class="main">    <div class="one"></div>
    <div class="two"></div>
    <div class="three"></div></div>
     <div>hello</div>
</body>